Prevost 3/8" Female Industrial Plug

All of these fittings are different and are not interchangeable.  Since I was starting from scratch, I've chosen to adopt the European High Flow Standard.  The reason for choosing this profile is the opening is the largest and has the least amount of parasitic loss. 

What that all means is that if you begin to use the Euro High-Flow Prevost S1 Couplers the I'm offering, you'll also need to replace any existing plugs installed on your tools.  These are inexpensive enough to do that easily.